The increasing physiological benefits of oryzanol on human health have generated the interest in developing commercially viable methods for the isolation of oryzanol from its various natural sources. The beneficial nutritional effects associated with oryzanol are discussed in depth (Piironen et al., 2000, Plant sterols: Biosynthesis, biological function and their importance to human nutrition. Journal of the science of food and Agriculture 80, 939-966). The expansive pharmaceutical application of oryzanol include hypocholesterolemic activity (Seetharamaiah and Chandrasekhara, 1989, Studies on hypocholesterolemic activity of rice bran oil, Artherosclerosis 78, 219-223), The emerging application of oryzanol in cosmetic preparations includes it usefulness in treatment of skin related disorders like melanin related disorder (Tatsu et al., 1993, (Eisai Co. Ltd.) JP 05225037) and minimizing the wrinkles in aged women (Tatsu et al., 1993, (Eisai Co. Ltd.) JP 0530526). In food application, oryzanol proves its usefulness as an antioxidant (Minami and Morito, 1982. Conditions for using oryzanol and its utilization in food, New Food Industries, 24(10) 49-53).
In the market there is demand for a product containing 40-55% oryzanol. In addition to food, pharmaceutical and cosmetic applications as discussed above, it has application as a special diet for racehorses (McConaghy and Vetclinstud (2001) South Australian Racehorse Owners Association (ASROA) Newsletter, pp. 4). All these beneficial effects of oryzanol in health care generated interest in developing viable separation method for oryzanol from the rice bran oil soapstock. Hence there exist a need for the development of simple and cost effective method for the production of oryzanol enriched fractions. The attractive cost competent byproduct (soapstock) as starting material for value addition is major motivation for work.
Reference cannot be made to many other works since almost all the reports that are available in literature employed acidic conditions, that to, without dehydration unlike the present work. Reference can be made to only work that is available that of Rao et al., (2002) [Process for the isolation of oryzanols from rice bran oil soap stock, U.S. Pat. No. 6,410,762] which refers to a process for the isolation of oryzanol from rice bran oil soapstock comprising saponification of the oil present in the soapstock with an alkali followed by neutralization of excess alkali and conversion of soapstock into anhydrous porous soapstock noodles and subsequent extraction by suitable unit operations. This process has the disadvantages of (1) tedious pretreatment and extrusion to form noodles and subsequent dehydration of them for prolonged duration (2) High mass transfer resistance and low interfacial area during the extraction of oryzanol due to larger size of anhydrous porous soapstock noodles.
Applicants have filed a PCT application PCT/IB02/05460 on Dec. 18, 2002 which relates to a simple process for crystallization of oryzanol from oryzanol enriched fraction. The process comprising (i) nonselective temperature assisted dissolution of oryzanol enriched unsaponifiable fraction in a suitable solvent mixture; (ii) fractional precipitation of mucilaginous interfering impurities; and (iii) crystallization of oryzanol from supernatant by either single method or combination of known methods to improve selectivity of crystallization. The present invention is different from the co pending application.
At the moment, the utility of soapstock is to generate the soap for toiletries and detergent industries. Attempts in the direction for effective utilization of the byproducts of RBO refining will definitely contribute to improve the economics of RBO refining. There is need to develop a more efficient separation processes for the isolation of value added products from byproducts of RBO refining. Oryzanol in one of the important value added product from byproduct (soapstock)